The impulse response, or simply IR, remains an abstract concept to many. But if we think of the impulse response literally as an audio track in a digital audio workstation (DAW) like Pro Tools, Logic or Reaper, it might bring welcome clarity.

Let’s start with Bob McCarthy’s excellent explanation. The impulse response describes the answer to a hypothetical question: “What would this Device Under Test (DUT) look like on an oscilloscope when driven with an (im)pulse?” (Figure 1)

An oscilloscope displays audible sound as alternating current (AC) with positive and negative polarity where the ideal pulse (known as a Dirac pulse) would look like an instantaneous rise followed immediately by a fall without overshoot. It contains every audible frequency, lasting for exactly one cycle, starting at the same time and level...